On my Autolite 4100 Carb can someone tell me if you adjust fuel/air mixture similar to Holley? There are 2 adjustment screws on the front. Are both screws for fuel/air mixture or is one for fuel & one for air. I know how to adjust Holley but I suspect this is different. 1st pic is passenger side of carb & 2nd pic is drivers side. Note: This car came from the High Altitude of the Rocky Mountains. My son & wife drove it back to Arkansas. They said it ran perfect but when they got out of the mountains it started idleing rough. It runs perfect but just idles rough. Also the exhaust smells like it is running very rich. I figure the adjustment needs to be tweaked a little to compensate for the altitude. Thanks, Mike
I assume clockwise for richer & counterclockwise for leaner? I tried leaning it slightly & it idled better but would cut out during acceleration. Any advise? Thanks, Mike
Those are idle mixture adjustments screws ... they do nothing for the mixture during acceleration ...
I have a 4100 sitting in the garage. I have heard great things about them when built correctly. How do you like it so far-assuming it is not giving problems? Seth
A note; The needles on 4100 and 2100 carbs control the fuel and not the air like other carbs. This is reverse of normal design. The air is fixed by internal design. By turning the needles in you lean the mix and get into stumble off idle. Normally this carb would have had plastic adjustment limiters on from the factory if made for a car application in the early 70s and later.
Mike, the car came from higher altitude to lower altitude. my money would be on it running too lean. also check the timing. i lived at sea level and moved to 5k feet. i had to take the carbs lean and was told to run the vehicle a couple of degrees advanced. when i drive back to visit sea level i have to adjust the timing to prevent damage. if it idles rich, he probably had the idle screws rich to compensate for the jets being a little too lean at idle.
